ArfGAP1 Activity and COPI Vesicle Biogenesis
ArfGAP1 Activity and COPI Vesicle Biogenesis
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DOI：
10.1111/j.1600-0854.2008.00865.x
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发表时间：
2009-03-01
期刊：
影响因子：
4.5
通讯作者：
Wieland, Felix T.
中科院分区：
文献类型：
--
作者：
Beck, Rainer;Adolf, Frank;Wieland, Felix T.
高尔基衍生外壳蛋白I （COPI）囊泡在早期分泌途径中介导运输。体外高尔基膜形成COPI囊泡所需的最小机制包括(i)异七聚体蛋白复合物涂层，（ii）小鸟苷三磷酸酶adp -核糖基化因子1 （Arf1）和（iii）作为涂层受体的跨膜蛋白，如p24蛋白。关于ArfGAP1在COPI囊泡生物发生中的作用，有各种不同的报道。在这项研究中，我们表明，与文献数据相反，ArfGAP1不是COPI囊泡形成所必需的。为了研究ArfGAP1在囊泡形成中的作用，我们将该酶滴定到一个定义的重构实验中，以形成和纯化COPI囊泡。我们发现Arf1GAP1的催化量显著降低了纯化COPI囊泡的产率，并且Arf1而不是ArfGAP1构成了COPI外壳的化学计量成分。结合有争议的报道和本研究的结果，我们提出了ArfGAP1在膜运输中的新作用。
Golgi-derived coat protein I (COPI) vesicles mediate transport in the early secretory pathway. The minimal machinery required for COPI vesicle formation from Golgi membranes in vitro consists of (i) the hetero-heptameric protein complex coatomer, (ii) the small guanosine triphosphatase ADP-ribosylation factor 1 (Arf1) and (iii) transmembrane proteins that function as coat receptors, such as p24 proteins. Various and opposing reports exist on a role of ArfGAP1 in COPI vesicle biogenesis. In this study, we show that, in contrast to data in the literature, ArfGAP1 is not required for COPI vesicle formation. To investigate roles of ArfGAP1 in vesicle formation, we titrated the enzyme into a defined reconstitution assay to form and purify COPI vesicles. We find that catalytic amounts of Arf1GAP1 significantly reduce the yield of purified COPI vesicles and that Arf1 rather than ArfGAP1 constitutes a stoichiometric component of the COPI coat. Combining the controversial reports with the results presented in this study, we suggest a novel role for ArfGAP1 in membrane trafficking.